Study of Diesel Air-Fuel Mixing and Combustion at High Injection Pressures in a Rapid Compression Machine

2012 ◽  
Author(s):  
I. Pribicevic ◽  
T. Sattelmayer
Keyword(s):  
Injection Pressure ◽  
Nozzle Diameter ◽  
Oh Radicals ◽  
Rapid Compression Machine ◽  
Spray Cone ◽  
Spray Penetration ◽  
High Injection ◽  
Fuel Mixing ◽  
Rapid Compression ◽  
Injection Pressures

Diesel air-fuel mixing and combustion have been investigated in a Rapid Compression Machine (RCM). The measurements were performed at high injection pressures up to 260 MPa and under reacting and non-reacting conditions. The spray was injected through solenoid-controlled multi-hole injectors. Two nozzles were applied with orifice diameters of 175 μm (D175) and 150 μm (D150), respectively. The visualization of the penetration of the liquid and the gaseous phase as well as the spray cone angle under evaporative, non-reacting conditions was carried out by the shadowgraph imaging technique in combination with a high speed camera. For combustion studies the flame luminosity of the flame as well as the chemiluminescence signals emitted by the OH radicals in the UV range were detected. Investigations revealed different behavior of the macroscopic spray characteristics with the two applied nozzles when increasing the injection pressure from 200 MPa to 260 MPa. With the larger nozzle diameter (D175) the spray penetration and the spray propagation velocity increase as the injection pressure is increased. On the contrary to that, with the smaller nozzle diameter (D150) an increase of the injection pressure had no effect on the spray velocity. With 260 MPa a higher spray penetration was only observed at the beginning of the injection due to the faster opening of the needle. The further propagation of the tip of the spray was similar with 200 MPa and 260 MPa. With both applied nozzles the injection pressure has little effect on the penetration length of the liquid phase. At an applied injection pressure of 200 MPa the near-nozzle spray angle is wider with D175, whereas similar spray angles were observed at 260 MPa. From the measurements in reacting atmosphere an earlier ignition of the fuel and a faster combustion could be shown with nozzle D150. In addition, a higher combustion pressure was measured. This can be attributed to better air-fuel mixing and a higher premixed portion, which was confirmed by the analysis of the spray angles in the far-nozzle region obtained from the shadowgraph images at non-reacting conditions.

Review of the Investigation of Fuel-Air Premixing and Combustion Process Using Rapid Compression Machine and Direct Visualization System

2013 ◽  
Vol 465-466 ◽  
pp. 265-269 ◽  
Author(s):  
Mohamad Jaat ◽  
Amir Khalid ◽  
Bukhari Manshoor ◽  
Siti Mariam Basharie ◽  
Him Ramsy
Keyword(s):  
High Speed ◽  
Combustion Engine ◽  
Early Stage ◽  
Combustion Process ◽  
Injection Pressure ◽  
Rapid Compression Machine ◽  
Mixture Formation ◽  
Visualization System ◽  
Optical Visualization ◽  
Rapid Compression

s :This paper reviews of some applications of optical visualization system to compute the fuel-air mixing process during early stage of mixture formation and late injection in Diesel Combustion Engine. This review has shown that the mixture formation is controlled by the characteristics of the injection systems, the nature of the air swirl and turbulence in thecylinder, and spray characteristics. Few experimental works have been investigated and found that the effects of injection pressure and swirl ratio have a great effect on the mixture formation then affects to the flame development and combustion characteristics.This paper presents the significance of spray and combustion study with optical techniques access rapid compression machine that have been reported by previous researchers. Experimental results are presentedin order to provide in depth knowledge as assistance to readers interested in this research area. Analysis of flame motion and flame intensity in the combustion chamber was performed using high speed direct photographs and image analysis technique. The application of these methods to the investigation of diesel sprays highlights mechanisms which provide a better understanding of spray and combustion characteristics.

Analysis of Mixture Formation and Flame Development of Diesel Combustion Using a Rapid Compression Machine and Optical Visualization Technique

2013 ◽  
Vol 315 ◽  
pp. 293-298 ◽  
Author(s):  
Amir Khalid ◽  
Bukhari Manshoor
Keyword(s):  
Fuel Injection ◽  
Injection Pressure ◽  
Exhaust Emissions ◽  
Combustion Characteristics ◽  
Diesel Combustion ◽  
Rapid Compression Machine ◽  
Mixture Formation ◽  
Optical Visualization ◽  
Flame Development ◽  
Rapid Compression

Mixture formation plays as a key element on burning process that strongly affects the exhaust emissions such as nitrogen oxide (NOx) and Particulate Matter (PM). The reductions of emissions can be achieved with improvement throughout the mixing of fuel and air behavior. Measurements were made in an optically-accessible rapid compression machine (RCM) with intended to simulate the actual diesel combustion related phenomena. The diesel combustion was simulated with the RCM which is equipped with the Denso single-shot common-rail fuel injection system, capable of a maximum injection pressure up to 160MPa. Diesel engine compression process could be reproduced within the wide range of ambient temperature, ambient density, swirl velocity, equivalence ratio and fuel injection pressure. The mixture formation and combustion images were captured by the high speed camera. Analysis of combustion characteristics and observations of optical visualization of images reveal that the mixture formation exhibit influences to the ignition process and flame development. Therefore, the examination of the first stage of mixture formation is very important consideration due to the fuel-air premixing process linked with the combustion characteristics. Furthermore, the observation of a systematic control of mixture formation with experimental apparatus enables us to achieve considerable improvements of combustion process and would present the information for fundamental understanding in terms of reduced fuel consumption and exhaust emissions.

scholarly journals Investigation of Puffing and Micro-Explosion of Water-in-Diesel Emulsion Spray Using Shadow Imaging

Energies ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 2281 ◽  
Author(s):  
Mhadi A. Ismael ◽  
Morgan Heikal ◽  
A. A. Aziz ◽  
Cyril Crua ◽  
Mohmmed El-Adawy ◽  
...  
Keyword(s):  
Droplet Size ◽  
High Speed ◽  
Elevated Temperatures ◽  
Injection Pressure ◽  
Image Processing Algorithm ◽  
Long Distance ◽  
Secondary Atomization ◽  
High Injection ◽  
Digital Microscope ◽  
Injection Pressures

Water-in-diesel emulsions potentially favor the occurrence of micro-explosions when exposed to elevated temperatures, thereby improving the mixing of fuels with the ambient gas. The distributions and sizes of both spray and dispersed water droplets have a significant effect on puffing and micro-explosion behavior. Although the injection pressure is likely to alter the properties of emulsions, this effect on the spray flow puffing and micro-explosion has not been reported. To investigate this, we injected a fuel spray using a microsyringe needle into a high-temperature environment to investigate the droplets’ behavior. Injection pressures were varied at 10% v/v water content, the samples were imaged using a digital microscope, and the dispersed droplet size distributions were extracted using a purpose-built image processing algorithm. A high-speed camera coupled with a long-distance microscope objective was then used to capture the emulsion spray droplets. Our measurements indicated that the secondary atomization was significantly affected by the injection pressure which reduced the dispersed droplet size and hence caused a delay in puffing. At high injection pressure (500, 1000, and 1500 bar), the water was evaporated during the spray and although there was not enough droplet residence time, puffing and micro-explosion were clearly observed. This study suggests that high injection pressures have a detrimental effect on the secondary atomization of water-in-diesel emulsions.

Experimental Investigations of Cycle-to-Cycle and Cylinder-to-Cylinder Variation of PCCI Combustion With High Injection Pressures

2010 ◽  
Author(s):  
S. Juttu ◽  
S. S. Thipse ◽  
Praveen Mishra ◽  
N. B. Dhande ◽  
N. V. Marathe ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Heat Release ◽  
Injection Pressure ◽  
Combustion Mode ◽  
Operating Range ◽  
High Injection ◽  
Wide Range ◽  
Significant Difference ◽  
Low Load ◽  
Injection Pressures

Recently HCCI combustion concept has gained the attention of industry and academia due to its potential to reduce NOx and PM emissions simultaneously from diesel engines. The HCCI concept also called as Partially-Premixed Charge Compression Ignition (PCCI) when heavy fuel like diesel is used as fuel. To achieve homogeneous mixture of diesel+air+residual gases, high injection pressures are required with fine atomization. The cycle-to-cycle and cylinder-to-cylinder variations in rail pressure and EGR ratio caused to variations in engine performance. In this study combustion stabilities and cycle-to-cycle variations of diesel engine operated in PCCI combustion mode were investigated at different fuel injection pressures on a 4-cylinder, 4-stroke diesel engine. The experiments were conducted with 500bar, 1000bar, 1500bar and 1800bar injection pressures at low load (IMEP = 2bar) and 50% load (IMEP = 8.5bar) at 2500 and 3000 rpm. No EGR was used at low load condition and 50% EGR was used at 50% load at all injection pressures. In-cylinder pressures of 100 cycles were recorded for each test conditions running with PCCI mode. Consequently, cycle-to-cycle variations of the maximum Rate of Heat Release (ROHRmax), maximum Total Heat Release (THRmax), IMEP and Pmax were analyzed and evaluated using Coefficient of Variation (COV) of each parameter. The significant difference in COV from cylinder-to-cylinder was observed at higher injection pressures. With high injection pressures, wide range of cycle-to-cycle variations were observed in engines operated in PCCI combustion mode limiting the injection pressure and operating range of engine. The results show that the injection pressure need to be optimized with respect to load to control the PCCI combustion at constant EGR ratio to minimize the cycle-to-cycle variations and also extend the operating range of PCCI mode.

Experimental Study on Spray Characteristics of N-Butanol/Acidic Oil/Diesel Blends

2014 ◽  
Vol 1008-1009 ◽  
pp. 1001-1005 ◽  
Author(s):  
Jian Wu ◽  
Yang Hua ◽  
Zhan Cheng Wang ◽  
Li Li Zhu ◽  
Wei Wei Shang
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Cone Angle ◽  
Injection Pressure ◽  
Air Entrainment ◽  
Mixing Ratio ◽  
Spray Characteristics ◽  
Spray Cone Angle ◽  
Spray Cone ◽  
Spray Penetration

In order to better research on the spray characteristics of biodiesel and n-butanol blends, an experimental study of spray characteristics of different fuel mixtures was investigated in a constant volume vessel using high speed photograph method, and analyzed the influence of different proportions of acidic oil biodiesel and n-butanol on the macroscopic parameters of spray penetration, spray cone angle and so on. The results show that with the increase of acidic oil biodiesel ratio, the air entrainment is weakened, spray penetration gradually increases and spray cone angle decreases under the same injection pressure and back pressure. After adding n-butanol in acidic oil biodiesel and diesel mixture fuel, the surrounding air entrainment is enhanced, and spray front end widen. With the increase of mixing ratio, spray penetration increases first, then decreases. The spray cone angle increases after adding n-butanol, and decreases with the increase of mixing ratio. The results show that adding n-butanol can be used as one of the methods to improve biodiesel spray characteristics.

Modified Single-Fluid Cavitation Model for Pure Diesel and Biodiesel Fuels in Direct Injection Fuel Injectors

2012 ◽  
Author(s):  
Kaushik Saha ◽  
Ehab Abu-Ramadan ◽  
Xianguo Li
Keyword(s):  
Saturation Pressure ◽  
Injection Pressure ◽  
Wall Roughness ◽  
Cavitation Model ◽  
Fluid Mixture ◽  
Fuel Injectors ◽  
Cavitation Inception ◽  
High Injection ◽  
Biodiesel Fuels ◽  
Injection Pressures

A cavitation model has been developed for the internal two-phase flow of diesel and biodiesel fuels in fuel injectors under high injection pressure conditions. The model is based on the conventional single-fluid mixture approach with modification in the phase change rate expressions and local mean effective pressure, considering the effects of viscous stresses and turbulent pressure fluctuations, and also takes into account the effects of turbulence, compressibility and wall roughness. The model is validated by comparing the model predictions of probable cavitation regions, velocity distribution, fuel mass flow rate and pressure with the experimental measurement available in literature. It is found that cavitation inception for biodiesel occurs at a higher injection pressure, compared to diesel, due to its lower saturation pressure. However, supercavitation occurs for both diesel and biodiesel at high injection pressures. RNG k–ε model for turbulence modeling is reliable by comparing its performance with realizable k–ε and SST k–ω models. The effect of liquid phase compressibility becomes considerable for very high injection pressures. Wall roughness is not an important factor for cavitation in fuel injectors.

Visualization of diesel spray and combustion from lateral side of two-dimensional piston cavity in rapid compression and expansion machine, second report: Effects of injection pressure and interval of split injection

2021 ◽  
pp. 146808742199306
Author(s):  
Chengyuan Fan ◽  
Keiya Nishida ◽  
Yoichi Ogata
Keyword(s):  
Combustion Process ◽  
Injection Pressure ◽  
Lateral Side ◽  
Two Dimensional ◽  
Split Injection ◽  
High Injection ◽  
High Injection Pressure ◽  
Compression And Expansion ◽  
Combustion Processes ◽  
Injection Pressures

The effect of split injection on the fuel spray and combustion processes in a rapid compression and expansion machine was investigated using the visualization process. A two-dimensional piston cavity, designed with the cross section of a reentrant piston, was installed in the combustion chamber to observe the combustion process from the lateral side. Combustion experiments were conducted with injection pressures of 80 MPa, 120 MPa, and 180 MPa and an O2 concentration of 15%. The spray/wall interaction, mixture distribution, and ignition location were investigated using the shadow method. Along with natural flame luminescence, different spray impinging behaviors on combustion process were studied. Furthermore, the combustion characteristics of in-cylinder pressure, apparent heat release rate, and combustion phase were recorded and analyzed simultaneously. The results showed that both high injection pressure and split injection with a longer interval effectively improved the combustion performance. In addition, when the pilot injection was advanced further, the injection interval had a larger influence in reducing soot generation, while the effect of high injection pressure on heat release decreased. Flame separation was found to occur at high injection pressures. It was observed that the flame separation caused by the strong spray momentum was beneficial for reducing soot generation owing to the greater fuel-air interaction area. The spray and combustion processes were investigated in detail, and the significant effects of different injection pressures and injection intervals on combustion performance with the split injection method were highlighted.

scholarly journals A study of diesel spray with unsteady and higher injection pressure using a rapid compression machine.

1990 ◽  
Vol 56 (526) ◽  
pp. 1837-1842
Author(s):  
Hideo TAKAHASHI ◽  
Seiichi SHIGA ◽  
Hidetoshi KOSHIBA ◽  
Takao KARASAWA ◽  
Toshio KURABAYASHI
Keyword(s):  
Injection Pressure ◽  
Diesel Spray ◽  
Rapid Compression Machine ◽  
Rapid Compression
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